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Number of bit-strings

Given an integer n, you are asked to calculate the number of different bit-strings of length n. Bit strings are strings that only have 0s and 1s.

Input

The only line of the input contains a single integer n (1 ≤ n ≤ 30)

Output

The program should print the number of bit strings of length n.

Examples

Input
Output
3
8
4
16

Explanation

3 → 000, 001, 010, 011, 100, 101, 110, 111 ⇒ 8 different bit-strings.
4 → 000, 0001, 0010, 0011, 0100, 0101, 0110, 0111, 1000, 1001, 1010, 1011, 1100, 1101, 1110, 1111 ⇒ 16 different bit-strings.
 
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